Predictors of postoperative myocardial ischaemia  The role of intercurrent arterial hypertension and other cardiovascular risk factors

Abstract

SummaryOne hundred and eighty-three patients were studied to examine the role of a number of risk factors in the development of silent ischaemia after general anaesthesia for general and vascular surgery. We collected evidence of cardiovascular risk factors using a binary questionnaire. The patients were monitored pre-and postoperatively using a Holter ECG monitor. Usable data were collected on 140 patients. Pre-operative silent myocardial ischaemia was found to be strongly associated with postoperative silent myocardial ischaemia (odds ratio: 10.8, 95% confidence intervals: 3.8-30.7). A history of hypertension, indicated by treatment with antihypertensive drugs, was associated with increased risk (odds ratio: 2.58, 95% confidence intervals: 1.12-5.96). A linear trend was found for risk associated with increasing admission systolic blood pressure (odds ratio: 1.20 for each 10-mmHg increase in systolic pressure, 95% confidence intervals: 1.01-1.42). An association between vascular surgery and postoperative silent myocardial ischaemia was also confirmed (odds ratio: 2.36, 95% confidence intervals: 1.1-5.1).

Acute peri‐operative beta blockade in intermediate‐risk patients

“…Importantly, these 281 patients [6,13,14] are in a lower cardiovascular risk category than those reported in peri-operative beta-blocker studies, where major cardiovascular complications have been reported (Table 2). The occurrence of cardiovascular outcomes over the 12 months postsurgery for the two patient groups is recorded in Table 4.…”

“…Values are number (proportion). In the comparator chronic beta-blocked group [6,13,14], the incidence of silent myocardial ischaemia was 38%. those patients exhibiting peri-operative SMI (p = 0.036).…”

“…Identification of a comparator group of non-cardiac surgical patients where peri-operative silent myocardial ischaemia and long-term cardiovascular outcomes were reported To make a valid comparison with other studies where the association between peri-operative SMI and major cardiovascular complications up to 12 months after surgery have been reported, we took data from three comparable published observational studies carried out in Oxford [6,13,14]. The studies were selected as the majority of the patients had undergone intermediate-risk surgery [3] or had £2 clinical risk factors using Lee's RCRI [12].…”

“…Studies of silent myocardial ischaemia (the comparator group) Patient demographics and surgical risk The SMI study by Higham et al [6] together with additional data from Higham et al [13] and Howell et al [14] provides us with data on late cardiovascular outcomes (up to 12 months) in 281 patients following vascular surgery and intermediate-risk surgical procedures (general and orthopaedic surgery) where peri-operative SMI (ambulatory ECG monitoring) was reported. The final data set comprised 107 patients exhibiting peri-operative SMI and 174 controls.…”

“…In the comparator studies [6,13,14] of peri-operative SMI, the patients were followed for 12 months after surgery to determine the incidence of major cardiovascular complications (cardiac death, myocardial infarction, heart failure, ECG ischaemia or unstable angina needing treatment, cardiac arrhythmias needing treatment and cerebrovascular events).…”